Honestly, it's just about doing what is easier at the time. Re-compiling an application in debug can be a pain sometimes, or getting back to a specific state within the application to inspect what is going on. Some have mentioned about hardware (which marches on with or without software running), but similarly part of a system where you only really control one sub-system/interface.

My print statements normally come when "I have no idea why this is breaking", and I start sanity checking the basics to make sure that things I previously thought were true, remain so.

Just recently I was doing something in C after a long time, and had something like this (simplified):

    #include <stdio.h>
    int main(){
      int a = 0; // Input from elsewhere
      switch(a){
        case 0 :
          printf("0\n");
          break;
        defult :
          printf("?\n");
          break;
      }
      return 0;
    }

It was late at night, it compiled, so I knew it wasn't a grammar issue. But after testing with printf()'s I realised that the default case was never being hit and performing the core action. It turns out 'defult' highlights in my editor and compiles fine in GCC. Turns out that any word in that location compiles fine in GCC. Nasty!